Many people have predicted, using a model like the one in panel

(b) of Figure 17.12 on page 570, that the price of natural resources should rise consistently over time in comparison with the prices of other goods because the demand curve for natural resources is continually shifting to the right, while the supply curve must be shifting to the left as natural resources are used up. However, the relative prices of most natural resources have not been increasing.

Draw a graph that shows the demand and supply for natural resources that can explain why prices haven’t risen even though demand has.